Four-year dynamic of vegetation on mounds created by zokors ( Myospalax baileyi) in a subalpine meadow of the Qinghai-Tibet Plateau

Abstract

The recovery of vegetation cover following soil disturbance by the plateau zokor ( Myospalax baileyi) was investigated from 2001 to 2004 in a subalpine meadow of the Qinghai-Tibet Plateau. Two adjacent plots were compared: one control community (undisturbed by zokors for over 5 years) and one disturbed community (with new mounds present before enclosure in year 2000). Vegetation on mounds tended to recover over time. Plant diversity, cover, biomass and density reached 88.5%, 87.9%, 73.1%, and 52.7% of the values for the control community, respectively, over the 4-year period when zokors were excluded. The edges around mounds showed a gradual increase in aboveground biomass and vegetation density from 2001 to 2004, which compensated for the lack of plant cover on the center of the mounds. The total number of species in the disturbed community increased from 15 in 2001 to 27 in 2004, and contained three alien species which were not found in the control plot, which contained 30 species. The average species diversity in mound sites (>1.8) was generally higher than that of the control plot (1.7). It is probable that plateau zokors are important for maintaining or restoring the disturbance-dependent elements of native plant communities. In addition, zokor disturbance resulted in a significant change in soil particle size, increased soil water content from about 20% to 25% and soil organic carbon content from 108 to 114 g/kg (0–20 cm soil layer) after 4 years of restoration. The improvement in soil quality might be associated with the rate of vegetation recovery following zokor disturbance. Therefore, through modulation of vegetation recovery, plateau zokors might be said to act as ecosystem engineers in alpine meadows.